About 2,500 Brazilian police and soldiers launched a massive raid on a drug-trafficking gang in Rio de Janeiro on Tuesday, arresting 81 suspects and sparking shootouts that left at least 60 suspects and four police officers dead, officials said.

The operation included officers in helicopters and armored vehicles and targeted the notorious Red Command in the sprawling low-income favelas of Complexo de Alemao and Penha, police said.

The police operation was one of the most violent in Brazil's recent history, with human rights organizations calling for investigations into the deaths.

Rio's state Gov. Claudio Castro said in a video posted on X that 60 criminal suspects were "neutralized" during the massive raid that he called the biggest such operation in the city's history. Some 81 suspects were arrested, while 93 rifles and more than half a ton of drugs were seized, the state government said, adding that those killed "resisted police action."

Rio's civil police said on X that four officers died in Tuesday's operation. "The cowardly attacks by criminals against our agents will not go unpunished," it said.

Residents scrambled for cover and shops closed their doors amid police claims that the gangs were using drones to fight back, Agence France-Presse reported.

Castro posted a video on X of what he described as a gang-controlled drone launching a projectile from the cloudy sky.

"This is how the Rio police are treated by criminals: with bombs dropped by drones. This is the scale of the challenge we face. This is not ordinary crime, but narcoterrorism," he said.

State officials said at least 50 of those killed were "indicated by police as suspected of being criminals," BBC News reported. Dozens of people were injured, including civilians caught in the crossfire, according to the BBC.

The United Nations' human rights body said it was "horrified" by the deadly police operation, called for effective investigations and reminded authorities of their obligations under international human rights law.

César Muñoz, director of Human Rights Watch in Brazil, called Tuesday's events "a huge tragedy" and a "disaster."

"The public prosecutor's office must open its own investigations and clarify the circumstances of each death," Muñoz said in a statement.

Footage on social media showed fire and smoke rising from the two favelas as gunfire rang out. The city's Education Department said 46 schools across the two neighborhoods were closed, and the nearby Federal University of Rio de Janeiro canceled night classes and told people on campus to seek shelter.

Suspected gang members blocked roads in northern and southeastern Rio in response to the raid, local media reported. At least 70 buses were commandeered to be used in the blockades, causing significant damage, the city's bus organization Rio Onibus said.

The operation Tuesday followed a year of investigation into the criminal group, police said.

Gov. Castro, from the conservative opposition Liberal Party, said the federal government should be providing more support to combat crime - a swipe at the administration of leftist President Luiz Inácio Lula da Silva.

Gleisi Hoffmann, the Lula administration's liaison with the parliament, agreed that coordinated action was needed but pointed to a recent crackdown on money laundering as an example of the federal government's action on organized crime.

Vice President Geraldo Alckmin and a number of ministers met in response to the operation on Tuesday afternoon. Chief of Staff Rui Costa requested an emergency meeting in Rio on Wednesday, with him in attendance as well as Justice Minister Ricardo Lewandowski.

Emerging from Rio's prisons, the Red Command criminal gang has expanded its control in favelas in recent years.

Rio has been the scene of lethal police raids for decades. In March 2005, some 29 people were killed in Rio's Baixada Fluminense region, while in May 2021, 28 were killed in the Jacarezinho favela.

While the Tuesday's police operation was similar to previous ones, its scale was unprecedented, said Luis Flavio Sapori, a sociologist and public safety expert at Pontifical Catholic University of Minas Gerais.

"What's different about today's operation is the magnitude of the victims. These are war numbers," he said.

He argued that these kinds of operations are inefficient because they do not tend to catch the masterminds, but rather target underlings who can later be replaced.

"It's not enough to go in, exchange gunfire, and leave. There's a lack of strategy in Rio de Janeiro's public security policy," Sapori said. "Some lower-ranking members of these factions are killed, but those individuals are quickly replaced by others."

The Marielle Franco Institute, a nonprofit founded by the slain councilwoman 's family to continue her legacy of fighting for the rights of people living in favelas, also criticized the operation.

"This is not a public safety policy. It's a policy of extermination, that makes the everyday life of Black and poor people a Russian roulette," it said in a statement.

AFP saw police in the Vila Cruzeiro neighborhood of Penha district guarding about 20 young people huddled together and sitting on the sidewalk, heads bowed, barefoot, and shirtless.

"This is the first time we've seen drones (from criminals) dropping bombs in the community," said a Penha resident, speaking on condition of anonymity.

"Everyone is terrified because there's so much gunfire," she added.

Raids in the favelas are common but this was the deadliest one yet. Until now the highest death toll came in a raid in 2021 that left 28 people dead.

Tuesday's operation ground traffic on many of the seaside city's main streets to a halt.

"We're left without buses, without anything, in this chaos and not knowing what to do," said Regina Pinheiro, a 70-year-old retiree, who was trying to return home.

Raid on gang in Rio de Janeiro leaves at least 64 people dead, including police officers